Rotary kiln chain hanger

ABSTRACT

An improved hanger for supporting a heat exchange chain in a rotary kiln and a method of connecting the chain thereto in a manner effective to prolong the service life of the chain by automatically and incrementally rotating the supporting end link about its own axis during a revolution of the kiln thereby to avoid concentrated wear of the link and premature failure.

United States Patent Woodward Apr. 9, 1974 [54] ROTARY KILN CHAIN HANGER1,910,873 5/1933 Zahn 432/l I8 [75] Inventor: Jackson H. Woodward, AppleValley Cahf' Primary Examiner-John J. Camby [73] Assignee: SouthwesternPortland Cement Attorney, 8 83 an Brace Company, Los Angeles, Calif.

[22] Filed: Mar. 26, 1973 211 App]. No.: 344,533 [57] ABSTRACT Animproved hanger for supporting a heat exchange [52] US. Cl. 432/28,432/1 18 hain in a rotary kiln and a method of connecting the [5 l Int.Cl. chain [hereto in a manner effective to prolong the er- Field OfSearch l vice life of the chain by automatically and incremen- 86 tallyrotating the supporting end link about its own axis during a revolutionof the kiln thereby to avoid References Cited concentrated wear of thelink and premature failure.

UNITED STATES PATENTS 3,526,394 9/1970 Howell, Jr 432/I18 7 Claims, 3Drawing Figures ROTARY KILN CHAIN HANGER This invention relates to aheat exchange chain for use in a rotary kiln, and more particularly toan improved hanger for connecting the end link of such a chain to thesidewall of the kiln.

It has long been common practice to equip rotary kilns, as for exampleof the type employed to manufacture cement clinker, with a multiplicityof heat exchange chains distributed about the entire inner periphery ofthe kiln at close intervals therealong. In this manner there is providedcurtains of such chains major portions of which become embedded in themass of raw material being converted to clinker after being heated bythe hot gasses passing along the interior of the kiln. This providesvery effective means for transfering the heat from the heated links intothe mass of material as the latter is tumbled back upon itself along thepower portion of the kiln during kiln rotation.

Those skilled in this art are aware of the long stand-- ing problemassociated with the use of such chains and the fact that one or morelinks at the end of the chain attached to the kiln wall fail prematurelyand long prior to the failure of the remaining links of the chain. Inconsequence, it has been necessary to take kilns out of operation forcostly reconditioning and replacement of worn chains. This is a verycostly and time consuming operation.

The foregoing and other shortcomings characteristic of the operation ofrotary kilns over many decades, are circumvented by the presentinvention and the service life of the heat exchange chains is greatlyprolonged. This is accomplished by an improved chain-hanger having anoverall length at least as great, and preferably somewhat greater, thanthe thickest encrustation of raw material which collects over a periodof time on the interior of the kiln before shutdown is necessary.Desirably but not necessarily, the hanger is constructed with an eyeletat either end with one eyelet used to pivotally support the hanger onthe kiln wall and the other being interlinked with the end link of thechain. At least the latter of these eyelets is designed to support theadjacent end link of the chain in a plane extending transversely of thekiln. This mode of support permits and facilitates rotation of the endlink about its own axis while major portions of the chain are submergedin the material undergoing treatment while shifting the point of contactbetween the end link and the hanger eyelet.

Accordingly it is a primary object of the presentinvention to provide animproved hanger for use in a rotary kiln to secure one end of a heatexchange chain to the kiln wall.

Another object of the invention is the provision of a kiln heat exchangechain hanger automatically providing for incremental rotation of thechain link interlinked therewith about the link axis during revolutionof the kiln.

Another object of the invention is the provision of an improved methodof suspending a heat exchange chain in a rotary kiln to increase theservice life thereof and to promote the periodic incremental rotationofthe link about its own axis.

Another object of the invention is the provision of an improved heatexchange chain hanger having provision for servicing the chain withoutneed for digging into or removing any portion of the encrustationcommonly accumulating on the inner sidewall of the kiln.

These and other more specific objects will appear upon reading thefollowing specification and claims and upon considering in connectiontherewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of theinvention is illustrated:

FIG. 1 is a cross-sectional partly diagrammatic view through a rotarykiln having an illustrative embodiment of the invention hanger installedtherein;

FIG. 2 is a fragmentary cross-sectional view on an enlarged scale takenalong line 2-2 on FIG. 1; and

FIG. 3 is a fragmentary cross-sectional view through an upper portion ofthe kiln wall after an encrustation layer of substantial thickness hascollected thereon.

Referring initially more particularly to FIG. 1, there is shown atypical rotary kiln 10 supported on idler rollers 11 for rotation abouta generally horizontal axis. The main body shell 12 of the kiln is linedwith refractory l3 and is provided with brackets 15 (FIG. 2) to whichchannel-shaped anchor rings 16 are attached, as by bolts 17. Rings 16are spaced at intervals, such as 12-18 inches, for a major interiorlength of the kiln beginning particularly at the entrance end. Rings 16are utilized to support a curtain of the heat exchange chains 20,20 eachchain being suspended from an individual elongated hanger 21 secured toring 16.

Chains 20 and hangers 21 are formed of high strength suitable heat andcorrosion resistant material, such as stainless steel. Typically, theindividual annular chain links 22 may have an internal diameter of threeinches' and a cross-section of seveneighths inch whereas hangers 21 havean overall length of approximately 1 foot and a cross-sectionaldimension of 1- /1. inches each supporting a chain 20 weighing lbs. ormore. The chains as here shown have a length somewhat less than theinternal diameter of the kiln. Usually the lower end of the outstretchedfully suspended chain barely clears the raw material 23, such as thatconventionally employed to make cement clinker in a cement kiln.

Referring to FIG. 2, it will be noted that hanger 21 has an eyelet 25 atone end interlinked with a bolt 26 passing through the flanges of ring16. Eyelet 27 at the lower end of the hanger is generally U-shaped andsupports an assembly bolt 28 passing through the end link 29 of chain20.

To be noted isthe fact that eyelet 27 is disposed to support end link 29in a plane extending crosswise of the kiln. This arrangement facilitatesincremental rotation of link 29 about its own axis during periods whenthe chain is not under tension as, for example, while the kiln isrotating counterclockwise from its 7 oclock position to the 2 or 3oclock position. During this period the chains in this portion of thekiln are submerged in the tumbling raw material while the latter isbeing carried up along the lower righthand quadrant to a position fromwhich it tumbles inwardly and downwardly over the underlying material.While this is occuring, 7

links 29 of each chain are jostled and moved through small incrementsthereby changing the point of contact between the [.D. of the ring andthe supporting area of eyelet 27, namely its point of contact with bolt28.

In operation, fuel and air are introduced into one end of the kiln andutilized to subject the raw material to heat treatment. The very hotgasses produced by the burning fuel and air mixture passes along theinterior of the kiln and through a series of curtains formed by amultiplicity of heat exchange chains 20 so as to heat the chains to ahigh temperature. As the kiln is rotated counterclockwise, these heatedchains fall onto the raw material and are subsequently submerged thereinby other raw material tumbling and gravitating downwardly from the lowerright hand quadrant of the kiln. In this manner, the raw material isbrought into intimate contact with a large mass of highly heated chains.

As the kiln continues in operation day after day,.an accumulation ofencrusted portions of the raw material collects in a layer 30. Thislayer increases in depth from day to day until the mid-length of thehangers is embedded therein as is clearly shown in FIG. 3. The hangerseventually become immobilized but eyelet 27 at the lower end remainsexposed as doesthe uppermost link 29 of each of the chains 20. At alltimes, the end links of non-tensioned chains are free to rotate andshift position with each revolution of the kiln. This action distributesthe worn zones and as well as the areas in which the temperature reachesa maximum between the chain and the hanger. In consequence, not only isthe service life of the chain and particularly that of the end links 29greatly extended, but should it become necessary for any reason tointerrupt operation of the kiln for inspection or for repair ,or damageto the ceramic lining, the connector bolts 28 between the chains andhangers 21 are fully exposed and readily accessible for replacement ofany chain. Thus, it is unnecessary to chip away any portion of theencrustation 30 to disconnect any one of the chains or to install a newone on any hanger which should be found without a heat exchange chain.

While the particular rotary kiln chain hanger herein shown and disclosedin detail is fully capable of attaining the objects and providing theadvantages hereinbefore stated, it is to be understood that it is merelyillustrative of the presently preferred embodimentof the invention andthat no limitations are intended to the detail of construction or designherein shown other than as defined in the appended claims.

I claim:

1. That improvement in a hanger for securing a heat exchange chain to arotary kiln which comprises, a chain of interlinked annular metal links,elongated hanger means for securing one end of said chain to theinterior sidewalls of a rotary kiln, said hanger means having a lengthadapted to be in excess of the thickness of an encrusted layer of thematerial undergoing treatment in the kiln and permitted to accumulatethereon, and means loosely connecting the end link of said chain to theinner free end of said hanger means in such manner that said end link isfree and tends to rotate through a short arc as the kiln rotates aboutits own longitudinal axis thereby to shift the area of contact betweenthe free end of said hanger means and the end link of said chain.

2. That improvement defined in claim 1 characterized in that saidelongated hanger means includes eyelet means at either end thereof, oneof said eyelet means being interlinked with the end link of said chainand the other of said eyelet means being interlinked with bracket meanssecured to the interior of said rotary kiln.

3. That improvement defined in claim 2 characterized in that one of saideyelet means includes removable fastener means extending transversely ofthe end of said hanger means.

4. That improvement as defined in claim 1 characterized in that saidchain end link lies in a plane substantially normal to the rotationalaxis of said kiln whereby said end link tends to rotate in smallincrements about its own axis as the kiln rotates.

5. That improvement as defined in claim 1 characterized in that saidhanger means includes eyelet means at each end thereof each includingpivot pin means lying parallel to one another and to the rotary axis ofsaid kiln and supporting said hanger means and said chain for pivotalmovement in a common plane generally normal to the kiln axis ofrotation.

6. That method of assuring incremental rotation of the suspension endlink of a rotary kiln heat exchange chain about the axis of said endlink despite the accumulation of encrustation on the interior of thekiln wall which method comprises, utilizing a chain having asubstantially annular end link, int'erlinking said substantially annularend link of said chain to the eyelet at the free end ofa long hangermeans with said end link lying in a plane generally normal to the rotaryaxis of the kiln, utilizing hanger means having a length such that itsinnermost end will lie inwardly of the thickest encrustation of clinkerpermitted to collect on the interior of the kiln before being removed,and supporting the other end of said hanger means from the interior ofthe kiln sidewall.

7. That method of prolonging the service life of a heat exchange chainin a rotary kiln which comprises connecting the annular end link of saidchain to the interior of a rotary kiln by interlinking said end link inan eyelet at the inner end of a chain hanger secured to and projectinginwardly from the sidewall of the kiln for a distance in excess of theradial thickness of a clinker layer permitted to collect and with theplane of said eyelet lying generally parallel to the rotational axis ofsaid kiln whereby said end link tends to rotate in small incrementsabout its own axis during one revolution of the kiln.

met es

1. That improvement in a hanger for securing a heat exchange chain to arotary kiln which comprises, a chain of interlinked annular metal links,enlongated hanger means for securing one end of said chain to theinterior sidewalls of a rotary kiln, said hanger means having a lengthadapted to be in excess of the thickness of an encrusted layer of thematerial undergoing treatment in the kiln and permitted to accumulatethereon, and means loosely connecting the end link of said chain to theinner free end of said hanger means in such manner that said end link isfree and tends to rotate through a short arc as the kiln rotates aboutits own longitudinal axis thereby to shift the area of contact betweenthe free end of said hanger means and means end link of said chain. 2.That improvement defined in claim 1 characterized in that said elongatedhanger means includes eyelet means at either end thereof, one of saideyelet means being interlinked with the end link of said chain and theother of said eyelet means being interlinked with bracket means securedto the interior of said rotary kiln.
 3. That improvement defined inclaim 2 characterized in that one of said eyelet means includesremovable fastener means extending transversely of the end of saidhanger means.
 4. That improvement as defined in claim 1 characterized inthat said chain end link lies in a plane substantially normal to therotational axis of said kiln whereby said end link tends to rotate insmall increments about its own axis as the kiln rotates.
 5. Thatimprovement as defined in claim 1 characterized in that said hangermeans includes eyelet means at each end thereof each including pivot pinmeans lying parallel to one another and to the rotary axis of said kilnand supporting said hanger means and said chain for pivotal movement ina common plane generally normal to the kiln axis of rotation.
 6. Thatmethod of assuring incremental rotation of the suspension end link of arotary kiln heat exchange chain about the axis of said end link despitethe accumulation of encrustation on the interior of the kiln Wall whichmethod comprises, utilizing a chain having a substantially annular endlink, interlinking said substantially annular end link of said chain tothe eyelet at the free end of a long hanger means with said end linklying in a plane generally normal to the rotary axis of the kiln,utilizing hanger means having a length such that its innermost end willlie inwardly of the thickest encrustation of clinker permitted tocollect on the interior of the kiln before being removed, and supportingthe other end of said hanger means from the interior of the kilnsidewall.
 7. That method of prolonging the service life of a heatexchange chain in a rotary kiln which comprises connecting the annularend link of said chain to the interior of a rotary kiln by interlinkingsaid end link in an eyelet at the inner end of a chain hanger secured toand projecting inwardly from the sidewall of the kiln for a distance inexcess of the radial thickness of a clinker layer permitted to collectand with the plane of said eyelet lying generally parallel to therotational axis of said kiln whereby said end link tends to rotate insmall increments about its own axis during one revolution of the kiln.